Dadi TJ30 type 3KW AC voltage regulator working principle - Power Circuit - Circuit Diagram

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

MOS power IC full range

Photocoupler

The electrical schematic is shown in the figure below. The whole machine can be divided into two parts: the main circuit and the control circuit. Vi and Vo are the input and output voltmeters respectively. The main circuit is the path of the AC power from the input terminal to the output terminal, including the air switch K1, the voltage regulation and through switch K2, the voltage regulating transformer T, the delay control relay J3, and the input and output terminals. The functions of the control circuit include power-on delay power transmission, stable output voltage, overvoltage protection and indication, undervoltage protection and indication.

1. Sampling voltage and reference voltage. The voltage regulating transformer T has two secondary windings, one of which is rectified by DQ1 bridge, and then divided by resistors R2 and R3, and the voltage dividing value on R3 is taken as the sampling voltage of the output voltage of the alternating current regulator. The 16V winding voltage is rectified by DQ2 bridge, the three-terminal regulator LM7812 is regulated, and the output DC12V voltage is supplied to the control circuit. The LED 2 of the LED indicates that the DC12V power supply is working normally. The integrated circuit A1 is a four-op amp HA17324, which is used here as a four-voltage comparator. The DC12V voltage is divided by the potentiometer RP and the resistors R4 to R8. A total of four divided voltage values ​​are taken as the reference voltage and sent to the corresponding input terminals of the four voltage comparators. The sampled voltage on resistor R3 is also sent to the input of the voltage comparator. The sampling voltage and the reference voltage are connected to the input of the comparator. The law of the comparator is to detect whether the output voltage of the AC regulator is higher than the rated value of 220V, the positive input terminal is connected to the sampling voltage, and the negative input terminal is connected to the reference voltage, such as A1.1 and A1. .2; Check if the output voltage of the AC voltage regulator is lower than the rated value of 220V, which is opposite to the above, such as A1.3 and A1.4. Understanding this law has reference significance for reading the circuit schematics of many brand AC voltage regulators, but the premise of this access law is: when the detection result is "Yes", the output of the voltage comparator is high. This happens to be what the relevant functional circuits need.

2. A high voltage requires a step-down. The output voltage regulation accuracy of the Dadi brand AC voltage regulator is set to ±4%. When the output voltage is exactly equal to 220V, adjust the potentiometer RP to make the reference of the inverting input terminal {6} of the voltage comparator A1.2. The voltage is also exactly equal to the sampling voltage connected to the {5} pin of the non-inverting input. If the output voltage rises (perhaps because the input voltage rises or the load current decreases), the sampling voltage also rises accordingly. The voltage comparator A1 The output of the .2 output terminal {7} is necessarily high, the transistor Q1 is turned on, the relay J1 is pulled in, the motor M is electrically rotated, and the carbon brush of the voltage regulating transformer is dragged until the output voltage of the alternating current regulator falls. Until 220V. The power supply circuit of the motor winding is: DC12V→J1 normally open contact→limit switch XK1→motor M→XK2→J2 normally closed contact→ground.

3. Low voltage requires boosting. If the output voltage is lower than 220V due to the decrease of the input voltage, etc., the output of the voltage comparator A1.3 {8} becomes higher, then the transistor Q2 turns on, the relay J2 pulls in, and the motor M turns electrically, but this When the polarity of the voltage on the winding of the motor is opposite to the previous one, the circuit is: DC12V → relay J2 normally open contact → limit switch XK2 → motor M → XK1 → J1 normally closed contact → ground, motor reverse rotation until output voltage Move back to 220V.
The limit switches XK1 and XK2 are installed on the regulating transformer. The limit position of the rotating range of the carbon brush is allowed. If the input voltage is too high or too low, the motor drags the carbon brush to the limit position and still cannot return the output voltage. 220V, the carbon brush holder will touch the limit switch, and the motor will be powered off and stopped to avoid overloading the motor.

4. Power-on delay power-on control This part of the circuit consists of integrated circuit A2 and its peripheral components. A2 is a dual op amp model HA17358, where the op amp is used as a voltage comparator. The voltage comparator's inverting input terminal {2} is connected with a reference voltage provided by the resistors R27 and R29, and the non-inverting input terminal {3} is connected to a charging circuit composed of a resistor R25 and a capacitor C7. When the power is on, the transistor Q5 is turned off, and C7 is charged from 0. Before the charging voltage on C7 reaches the {2} foot reference voltage, the output of the A2 is {1} is low; when the voltage on C7 reaches or exceeds {2 } When the voltage is applied, the {1} foot potential becomes high, the transistor Q6 is turned on, the relay J3 is closed, and its normally open contact is closed. The 220V voltage of the voltage regulating transformer is sent to the output of the AC voltage regulator via the J3 contact. The boot delay is over. This process takes about 5 minutes. Power-on delay power transmission is mainly to protect the safety of air conditioners, refrigerators and other equipment. If there is no such requirement, press the quick-start self-locking button AN, and the power-on delay time will be shortened to 2~3 seconds. This is because the capacitor C7 is charged by the resistor R26 having a resistance of only 10 kΩ, and its charging time constant has been significantly reduced. During the power-on delay period, the LED 4 is lit, indicating the current working state. When the AC voltage regulator is powered off, the capacitor C7 will be quickly discharged through the diode D2 to ensure that even after a short power failure, the C7 will resume charging from 0. The output of the AC regulator must be re-routed. The delay can only be sent out to ensure the safety of the electrical equipment.

5. Overvoltage protection circuit. It consists of integrated circuit A1.1 and peripheral circuits. When the voltage is higher, the motor brush is used to adjust the carbon brush to the limit position (at this time, because the limit switch XK1 acts, the motor stops rotating), and the output voltage still reaches or exceeds 1.1 times of 220V, the voltage comparator A1 The output of the .1 pin becomes high level, the transistor Q5 is turned on by the diode D1, the capacitor C7 is quickly discharged, the voltage of the comparator A2 output terminal {1} ​​is turned low, the relay J3 is released, and the AC is cut off. The voltage output of the press protects the electrical equipment. After the overvoltage protection, the LED 1 is lit, indicating that the power failure is caused by overvoltage.

6. Undervoltage protection circuit. It consists of integrated circuit A1.4 and triodes Q3, Q4 and other components. If the voltage is low and the transformer is adjusted to the maximum, and the output voltage is still lower than 0.9 times of 220V, the output of the voltage comparator A1.4 is changed from low to high, through the resistor R20 and After a short time delay of the capacitor C4 charging loop, the transistor Q3 is saturated, Q4 is turned off, and the high potential of the Q4 collector is saturated and turned on by the diode D3, which finally causes the relay J3 to be released, and the output of the alternating current regulator is powered off. When the voltage is under voltage, the LED 3 is lit, indicating that it is currently under voltage. If the consumer is allowed to operate undervoltage, the diode D3 can be removed, so that only the LED is instructed and uninterrupted when the voltage is undervoltage.

It can be seen from the above analysis that once the potentiometer RP is adjusted, the action thresholds of the boost control, the buck control, the overvoltage protection and the undervoltage protection are automatically generated, which greatly reduces the production and debugging under the premise of ensuring the voltage regulation accuracy. And the amount of work required for repairs.